AOC 2022 11

1.exs

parser = ~r/Monkey (\d):\s.*items:([\d,\s]*)\s*Operation:\snew\s=\sold\s([*+])\s(.*)\s*Test:\sdivisible\sby\s(\d{1,2})\s*.*(\d)\s+.*(\d)/

monkeys = 
  System.argv()
  |> List.first()
  |> File.read!()
  |> String.split("\n\n", trim: true)
  |> Enum.map(fn monkey -> 
    Regex.run(parser, monkey, capture: :all_but_first)
    |> List.update_at(0, &String.to_integer/1)
    |> List.update_at(1, & String.trim(&1) |> String.split(", ") |> Enum.map(fn i -> String.to_integer(i) end))
    |> List.update_at(4, &String.to_integer/1)
    |> List.update_at(5, &String.to_integer/1)
    |> List.update_at(6, &String.to_integer/1)
    |> Enum.concat([0])
  end)
  
Enum.reduce(0..19, monkeys, fn _round, monkeys -> 
  monkeys
  |> Enum.reduce(monkeys, fn [idx, _items, op, amt, test_denom, true_target, false_target, _], monkeys -> 
    monkeys 
    |> Enum.at(idx) 
    |> Enum.at(1)
    |> Enum.reduce(monkeys, fn item_code, monkeys -> 
      int_amount = if amt == "old", do: item_code, else: String.to_integer(amt)
      
      new_item_code = 
        Kernel
        |> apply(String.to_existing_atom(op), [item_code, int_amount])
        |> Integer.floor_div(3)
      
      test = Integer.mod(new_item_code, test_denom) == 0
      
      target_monkey = if test, do: true_target, else: false_target
      
      monkeys
      |> List.update_at(idx, fn monkey -> List.update_at(monkey, 7, & &1 + 1) end)
      |> List.update_at(target_monkey, fn monkey ->  List.update_at(monkey, 1, & &1 ++ [new_item_code]) end)
    end)
    |> List.update_at(idx, fn monkey -> List.replace_at(monkey, 1, []) end)
  end)
end)
|> Enum.map(fn [_, _, _, _, _, _, _, handle_count] -> handle_count end)
|> Enum.sort()
|> Enum.take(-2)
|> Enum.reduce(fn count, total -> count * total end)
|> IO.inspect

2.exs

parser = ~r/Monkey (\d):\s.*items:([\d,\s]*)\s*Operation:\snew\s=\sold\s([*+])\s(.*)\s*Test:\sdivisible\sby\s(\d{1,2})\s*.*(\d)\s+.*(\d)/

monkeys = 
	System.argv()
	|> List.first()
	|> File.read!()
	|> String.split("\n\n", trim: true)
	|> Enum.map(fn monkey -> 
		Regex.run(parser, monkey, capture: :all_but_first)
		|> List.update_at(0, &String.to_integer/1)
		|> List.update_at(1, & String.trim(&1) |> String.split(", ") |> Enum.map(fn i -> String.to_integer(i) end))
		|> List.update_at(4, &String.to_integer/1)
		|> List.update_at(5, &String.to_integer/1)
		|> List.update_at(6, &String.to_integer/1)
		|> Enum.concat([0])
	end)
	
lcm = Enum.map(monkeys, & Enum.at(&1, 4)) |> Enum.product()
	
Enum.reduce(1..10000, monkeys, fn round, monkeys -> 
	monkeys
	|> Enum.reduce(monkeys, fn [idx, _items, op, amt, test_denom, true_target, false_target, _], monkeys -> 
		monkeys 
		|> Enum.at(idx) 
		|> Enum.at(1) 
		|> Enum.reduce(monkeys, fn item_code, monkeys -> 
			int_amount = if amt == "old", do: item_code, else: String.to_integer(amt)
			
			new_item_code = 
				Kernel
				|> apply(String.to_existing_atom(op), [item_code, int_amount])
				|> rem(lcm)
				
			test = Integer.mod(new_item_code, test_denom) == 0
			
			target_monkey = if test, do: true_target, else: false_target
			
			monkeys
			|> List.update_at(idx, fn monkey -> List.update_at(monkey, 7, & &1 + 1) end)
			|> List.update_at(target_monkey, fn monkey -> List.update_at(monkey, 1, & &1 ++ [new_item_code]) end)
		end)
		|> List.update_at(idx, fn monkey -> List.replace_at(monkey, 1, []) end)
	end)
end)
|> Enum.map(fn [_, _, _, _, _, _, _, handle_count] -> handle_count end)
|> Enum.sort()
|> Enum.take(-2)
|> Enum.reduce(fn count, total -> count * total end)
|> IO.inspect